Spatially encoded picoliter droplet groups for high-throughput combinatorial analysis

Most current droplet microfluidic devices are limited to processing one single sample or one single assay in a single device due to inconvenient sample loading and unstable droplet generation when switching inputs. In order to maximize the capability of a single droplet device, we have developed a novel nanoliter-picoliter (nL-pL) device capable of handling multiple samples and assays. Our device can generate spatially encoded groups of thousands of picoliter droplets from different in situ assembled nanoliter plugs. The plugs can be uniquely assembled in an automated manner prior to picoliter droplet generation. We demonstrate the ability of our nL-pL device to generate distinct picoliter droplet groups with high stability and uniformity through a specific isolation valve design. This new device may find important applications in rapid bacterial identification, quantification, antibiotic susceptibility testing (AST), drug screening as well as single cell screening.